All About Bees: The Great Garden Pollinators

Bees play an important role in maintaining biological balance in our environment and recycling soil nutrients. Learn all about bees in this excerpt from "Bees, Wasps, and Ants" by Eric Grissell.

By Eric Grissell

| May 6, 2013

“Bees, Wasps, and Ants,” by Eric Grissell gives an in-depth look at bees and the important role insects have in gardens.Cover Courtesy Timber Press, Inc.

It is currently hypothesized that bees are simply pollen-collecting wasps.Photo By Fotolia/mch67

Bees are one of the most important insects to us. Not only are they great garden pollinators, they maintain biological balance and recycle soil nutrients. Learn all about bees — from the difference between bees and wasps to colony collapse disorder in Bees, Wasps, and Ants (Timber Press, 2010) by Eric Grissell. The following excerpt was taken from chapter 8, "The Garden’s Pollinators: Bees."

The Garden’s Pollinators: Bees

Mention the word bee and our perspective on the subject immediately turns to the honey bee. On a good day we might even follow this with thoughts of bumble bees or carpenter bees. At that point most of us will have run out of any sorts of thoughts about bees at all. But what of the resin bees, don’t they deserve our thoughts as well? Or the mason bees and sweat bees? The leafcutter bees? The cuckoo bees? The mining and digger bees? The green bees and yellow-faced bees? The squash and gourd bees? The plasterer, polyester, or cellophane bees? The carder bees? And my favorite moniker of all, the shaggy fuzzyfoot bee? There are bees galore and many more, and some deserve a bit of attention now and then, so in this chapter we’ll examine aspects of bee life that may prove interesting, if not useful, to the gardener.

Bees, it is currently hypothesized, are simply pollen-collecting wasps. That is, some predatory wasps began to collect pollen instead of insect prey to feed their young. The pollen wasps (subfamily Masarinae) are an example of a possible intermediary step in the road to beedom. The main difference between bees and wasps (as well as other Hymenoptera) is that the bees have branched or feathery hairs and the wasps have simple hairs. During this evolutionary transition, it is believed that the unmodified body hairs of wasps became branched to better trap pollen grains. In addition, structures associated with the legs became modified to scrape and consolidate pollen from these hairs. In some cases the pollen was formed into packets and stored in the corbicula (a sort of pollen basket) on the hind leg, and in others, pollen accumulated in hairs on the underside of the abdomen. Transporting one grain of pollen at a time would have been rather time consuming, so consolidating and transporting as much pollen as possible soon became the imperative. Thus, when you get right down to basics, bees are just fuzzy wasps.

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Compared to predatory wasps, bees are much less diverse in what they feed their young: in every case pollen and nectar and rarely plant oils. If we ignore the honey bee, which has about as complex a life as is possible, the basic life of a bee is arguably less complex than that of a predatory wasp. Within bees there are levels of sociality from solitary to eusocial, but analogous behaviors may be found in the wasps. Some bee species are thieves (that is, cleptoparasitoids) of other bees, in which case their larvae eat pollen provisions given to the host bee larvae, thus inadvertently starving the host larvae. This behavior is also found in predatory wasps, though the food is other insects, not pollen. And there are a few colonial bee species that are social (or brood) parasites, invading a host colony and living among the worker bees as if they belonged there — another behavior found in social predatory wasps.

As with predatory wasps, the majority of bees are solitary, building and provisioning nests by themselves. Solitary bees are much less well known than the eusocial kinds (that is, honey bees and bumble bees). Of all the solitary sorts, the large carpenter bee (Xylocopa) is likely to be the most readily recognized member of the group. The leafcutter bees are more likely noted by what they do than their actual appearance. They are responsible for the circular cutouts in leaves of roses and other plants. Other than these few examples, there is a tremendous variety of lesser-known characters about which much can be said.

Social bees are defined by the presence of two or more individuals occupying the same nest. Unfortunately this causes some confusion when attempting to segregate bees into groups of behaviors we might find convenient. Therefore, most of us likely think of social (that is, eusocial) bees only in terms of honey bees or bumble bees in which many individuals work together and are directed by the queen. In temperate areas of the world such as the United States and Europe, members of the true eusocial habit are limited to the two groups just mentioned, but in tropical regions there are other groups of similarly social bees called stingless bees (entirely eusocial) and orchid bees (some species eusocial). There are various levels of sociality within bee groupings, including communal, quasisocial, semisocial, sub­social, and eusocial (that is, honey bees, bumble bees), each a little more complicated than the preceding. The distinctions, however, between these categories are not very clear, even to specialists, and species within families and even within genera may be found in several of these categories. Rather than get bogged down in hair-splitting minutia, I’ll mention only a few of the more straightforward examples of social behavior likely to be found in the bees in or around our gardens.

To put our woeful ignorance of bees somewhat in perspective, as of October 2008 several checklists of all the valid bee species names in the world placed the number between 19,342 (Discover Life, Apoidea species) and 19,511 (World Bee Checklist; see the table of hymenopteran families). As a result of these overwhelming numbers and our obsessive preoccupation with the honey bee, the behavior of most bees, including even the common bumble bee, remains largely unknown to the general public. In discussing the various groups of bees below, I include numbers simply to give the gardener some idea of what is taking place in nature when we are not looking. These figures are taken from the Discover Life site because it is interactive and the easier source from which to extract the necessary information.

Six families of bees are fairly widespread throughout the world, with a seventh (Stenotritidae) found only in Australia (Michener 2007). Of the world’s bee species, roughly one-third (that is, some 6800) are found in North America (Michener 2007). There is no easy way to organize bees into coherent groups based on their biology, shapes, sizes, or degree of sociality, so I’ve opted simply to discuss them by family unit since there are so few.

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I’ll also mention some useful additional sources of information about bees as we progress through the families. As you can imagine, hundreds of books, both technical and popular, have been written about the honey bee, and a search at any internet store selling new or used books will turn up more titles than is humanly possible to read. Conversely there are many fewer books on bees in general, and these tend to be technical, terribly expensive, and tending toward the economics or taxonomy of specific groups. By far, the most comprehensive book on bees, at 953 pages, is Charles Michener’s The Bees of the World (2007), which summarizes everything we know about bees and includes about 2500 references for those who wish to delve further into the subject. I have gleaned much useful information from this source. Unfortunately, it is expensive, highly technical, and largely taxonomic, though it does encapsulate the biology of every group known to humankind. A much more user-friendly overview of bees from a biological standpoint is Bees of the World by O’Toole and Raw (1999). For diehard bee fans there is even an annual workshop called “The Bee Course” held at the American Museum of Natural History’s Southwestern Research Station in southeastern Arizona.

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